Technical Abstract:
Slickspot peppergrass (Lepidium papillerferum) is a rare ephemeral endemic plant found in Southwest Idaho's high desert. The goal of this research was to determine whether counting the number of live
plants growing on the soil surface was an accurate determination of the viability of this species. A field test was performed to determine the number of viable seeds of slickspot peppergrass growing in slick spots. Slick spots are small depressions that typically have a crusted or smooth surface of fine silty soil with an excess of exchangeable sodium. Slick spots sampled contained both seed-producing flowering plants and non-flowering biennial rosettes. On average there were twice as many biennial rosettes than flowering plants. Seeds were found throughout the soil profile to a depth of 15 cm in sampling locations inside and outside the slick spots. More seeds were found in the surface soil as compared to the lower soil depths. We found 144, 18, and 14 seeds at 5, 10 and 15-cm soil depths, respectively, and the seeds had a greater germination percentage (54%, 43%, and 18%). Our results show that measuring only plants growing above ground on a site and not accounting for dormant seeds in the seed bank will probably underestimate the future growth potential of the peppergrass population.